“Consider this: in 1929, an average American
would have had to pay 1.49 per cent of her or his annual
income of $84.90 to buy a barrel of crude oil, which
then sold for $1.27. Fifty years later, in the wake
of the Iranian revolution, oil prices soared to $31.61.
But the annual earnings of the average American rose
had risen even more sharply, to $7,956. That meant that
a barrel of oil would cost them just 0.39 per cent of
their earnings – a quarter of what it did in 1929.

“The numbers for recent years are even more revealing.
In 2008, oil prices soared to $96.91 – very similar
to now. But the average American earned $35,931 that
year, which means a barrel of oil would cost them 0.26
per cent of their earnings: well below what it would
have in the oil-shock 1970s.”